Control switch device for hydeaulic accumulators



W. PIRWITZ Dec. 1, 1936.

CONTROL SWITCH DEVICE FOR HYDRAULIC ACCUMULATORS Filed Feb. 20, 1934 2Sheets-Sheet 1 Dec. 1, 1936. w. PIRWITZ CONTROL SWITCH DEVICE FORHYDRAULIC ACCUMULATOR Filed Feb. 20, 1934 2 Sheets-Sheet 2 Patented Dec.1, 1936 UNITED STATES PATENT OFFICE CONTROL SWITCH DEVICE FOR HYDRAULICACCUMULATOBS Application February 20, 1934, Serial No. 712,204

In Germany March I, 1933 Claims.

My invention relates to liquid level control switches for hydraulicaccumulators which contain water and air under high pressure and inwhich the water is directly charged by the air 5 without theintermediary of a piston.

In accumulators of this type, it is necessary to prevent the water,contained in the accumulator from rising or falling beyond predeterminedlevels. For this purpose switch devices are provided which control thesupply and Cllt-Ofi means for the compressed water in accordance withthe water level in the accumulator.

A switch device of known construction comprises a plurality ofoscillatory or tilting switches, provided simply at each controllinglevel in the pressure chamber of the accumulator. Each of such switchescomprises a. diving bell and a mercury tube switch as electricalcontactor, both being pivotally supported in the pressure chamber bymeans of suitable mechanical means, such as a lever. The diving bellsare adapted to be oscillated or tilted about their pivot in oppositedirections depending upon the water in the accumulator rising or fallingas the case may be, and to 5 operate thereby on the contactors whichopen or close circuits for controlling the supply and cutoff means forthe compressed water according to .its level. The pivots of the switchesare supported by a mounting, which is attached to the Wall of thepressure chamber.

In this known construction, the arrangement of the contactors inside thepressure chamber makes it necessary to have the contactors extendoutside the'pressure chamber through an insulating plug. Because of thevery high pressures in the accumulator the passing of the conductorthrough this plug must be made very carefully to avoid leakage.Furthermore, to withstand the high pressures,.the mercury tube switchmust be of particularly rugged construction. Also, it may be considereda drawback to have the electrical part of the switch located entirelyinside the pressure chamber and therefore not visible from outside sothat its condition and its operation can not be examined when at work.

The present invention has as its object to provide a switch device forhydraulic accumulators of the above type in which said drawbacks areavoided.

This is accomplished in the first place by the electrical part of theswitch being bodily separated from its mechanical part and the formerbeing situated outside the pressure chamber. For

, transferring the oscillating movement of the diving bells to thecontactors. the diving bells are associated with permanent magnets so asto form an oscillating scale which when not immersed has an overload atits diving bell end which overload is compensated when the water in theaccumulator rises.

With this arrangement only the diving bells, the permanent magnets andtheir pivots remain inside the pressure chamber all which parts caneasily withstand high pressures. As the electrical part of the switch islocated outside the pressure chamber, it is both visible and accessiblefrom the outside when at work, and the pressure chamber need not berelieved or emptied when the electrical part has to he removed foroverhauling and resetting as the case may be. The contactor can he amercury tube switch of con ventional type, but it is to he understoodthat the invention is not limited to a special type of electricalcontactor.

Another feature of this invention is that the mercury tube switches arestationary, the movements for making and breaking contacts being thenperformed by armatures pivotably supported inside the tubes and actuatedby the per manent magnets.

The latter, according to this invention, have the form of a horse shoe,which is so arranged relative to its respective mercury tube switch thatthe contact armature oi the tube is adapted to pivot in the spacehetween the limbs or pole pieces of the magnets. the armatures arepositively pulled both to their make and break positions by magneticforce, and vibrations of the armatures and of the relays controlled bythem can not occur.

The magnetic pull oi the armature in both directions of its oscillatingmovement enables the armature to be balanced with respect to its pivot.As the weight of the armature therefore need no longer be overcome formoving the same, the permanent magnet and the diving hell can be madesmaller than would be the case otherwise. In this way the sensitivity ofthe control is still further increased.

A further advantage is that the small dimensions of the oscillatingswitch mechanism require only small recesses in the pressure chamber, ascompared with the known construction above referred to.

The high sensitivity of the control makes it possible to control anumber of contactors by one oscillating switch mechanism only. This isad vantageous because thereby the number of parts located inside thepressure chamber of the ac umulator is reduced and the thickness of itswalls has to be weakened at fewer places only.

Further objects and advantages will appear upon reference to thefollowing description and the accompanying drawings in which Figs. 1 and2 are sectional elevations of water vessels of an hydraulic accumulatorfitted with switches embodying the present invention.

Figs. 3, 4 and 5 are longitudinal sections, along line 33 of Fig. 6,showing the switch in three different positions.

' Fig. 7 is an outer side view of a modification in which the switch isassociated with more than one contactor. v

Fig. 8 is a cross section, along line 3-3 of Fig. 7.

In Fig. l, I indicates the water vessel of a hydraulic accumulator ofwell-known construction, which is filled with compressed water and air,the water being directly charged by the air without the intermediary ofa piston. Pipes 2 and 3 are provided for filling the water vessel withcompressed air and water respectively. The supply 'and cut-oft means forthe water vessel which are connected to pipes 2 and 3 are not shownhere, as they do not form any part of my invention and may be ofconventional form.

In order that the accumulator can be used without trouble, means areprovided preventing the water in vessel I from rising above level a orfalling below level b. For this purpose, switches I and II are arrangedat the height of the levels a and b respectively, the switch I.forstopping the feed pump of the accumulator and the switch II for closingthe cut-off valve, when the water has reached the respective levels. Athird switch III is arranged a short distance below level a at level cfor restarting the feed pump, when the water has fallen from level a. tolevel 0. This way of controlling hydraulic accumulators is well knownand forms no part of the present invention.

The two embodiments of Figs. 1 and 2 differ only from another in as faras in the embodiment shown in Fig. 1, the switches are arranged in thewater vessel I itself, while in the embodiment shown in Fig. 2, theswitches are arranged in a pipe system communicating with vessel I. Inthe latter case, the two switches I and III are both mounted in the samecasing 4, and the switch 11 in a separate casing l. Casings 4 and 5 areconnected with each other by pipe 3, whereas casing l is connected tothe air chamber of vessel I by curved pipe I and casing 5 is connectedto the water chamber of vessel I by curved pipe 3. Valves 8 are arrangedabove and below the casings l and 5 respectively, for cutting of! thecom municating system from vessel I,, so that the switches can be fittedto the system and removed again without having to relieve pressure fromvessel I.

In Figs. 1 and 2, the switches I-III are represented in a diagrammaticway. Each switch comprises an oscillating mechanical part and asubstantially stationary electrical part. The mechanical part is locatedinside and the electrical part outside the pressure chamber, this latterterm being used in this connection in a broad sense, so as to indicatethe space enclosed both by the water vessel I and the pipe systemcommunicating therewith.

The switches will now be more fully described with reference to Figs. 3to 8 inclusive.

Each switch comprises a diving bell III which forms together with apermanent magnet II a scale-like structure, fulcrumed at II.

The diving bell end of the scale is somewhat heavier than the magnet endwhen not immers as shown by Fig. 3. When, however, the water rises andrushes into diving bell I0, so that the latter becomes more and moreimmersed, the

readily fitted and removed as required. For reasons which will beapparent later, the mounting is of non-magnetic material, e. g. bronze,whereas wall I4 of the pressure chamber can be made of magneticmaterial, such as steel.

A contact armature I6 is pivoted at IT to mercury tube switch I5 andcounter-balanced with respect to its pivot, electrodes I8a and IN)being.

provided both at the pivot and at the outer end of the armaturerespectively. Electrode I is constantly dipping into a cup-shapedprojection ISa of tube I5, filled with mercury, whereas electrode I8b isso disposed as to dip into a mercury filled cup-shaped projection I3b ornot, making or breaking contact according to the position of armatureIll. The inner end of armature I6 extends into the field of magnet IIand is thereby controlled as to its position, when the magnet isoscillated together with diving bell II) about pivot I2.

In the embodiments shown, the magnet II has horse-shoe form. Its twolimbs or pole pieces I Ia and Ill: embrace the inner end.of tube I5, sothat armature I6 is pivotally mounted between the two limbs and can bepulled in either direction and held in its end positions by magneticforce.

In Fig. 3, only the lower limb I lb operates upon armature I6. The innerend of the latter which is close to the magnet will therefore be loweredand its outer end be raised, and the contact will.

When the water in the pressure chamber rises,

the air in the diving bell will be trapped, and on a further rise of'thewater level, the diving bell will be raised by its buoyancy as shown inFigs. 4 and 5 so that the scale structure performs an oscillatingmovement about pivot I2.

In Fig. 4, the diving bell and the magnet have reached an intermediateposition, the limbs Ila and Nb of the magnet being equally far away fromarmature I3 so that the latter will remain in its position.

In Fig. 5, the diving bell is still more raised. The upper limb Ila ofthe magnet has now come so close to armature I8 as to pull it upwardly,and the electrode 13b now dips into the mercury filled cup I9b, so thatthe contact is made. This position is shown in Figs. 1 and 2 withrespect to switches II and III.

In Figs. '7 and 8, a modified embodiment is shown, in which two mercurytubes I! are controlled by a single magnet, the two tubes being arrangedside by side in the same mounting I3. The tubes are of the same type asthe one above described, the mechanical part of the switch being alsoleft unchanged, so that further description is not deemed necessary. Bythe parallel arranging of a number of contactors, it is possible tocontrol at one time a plurality of circuits by a single oscillatingmovement of the switch, which may be of importance when the accumulatoris fed by a plurality of pumps which are to be started in series.

I claim:

1. A control switch mechanism comprising a permanent magnet having apair of spaced arms, said magnet being pivoted for unitary oscillationof said arms in the plane thereof, a switch armature also pivoted foroscillation in the same general direction as said magnet and having aportion thereof extending between said magnet arms, and means limitingoscillatory movement of said armature to an extent such that when themagnet is swung in one direction said armature is swung in one directionby the magnetism of one of said arms and when the magnet is swung in theother direction the armature is swung in the other direction by themagnetism of the other of said arms.

2. A control switch mechanism comprising a pair of spaced magneticmembers connected together and pivotally mounted for unitary oscillationin the plane thereof, and a switch armature pivoted for oscillation inthe same general direction as said members and having a portion thereofdisposed with respect to said members, and the mechanism including meansfor limiting oscillatory movements of said armature, so that when themembers are swung in one direction one of the same is efiective by itsmagnetism to swing said armature in one direction, and when the membersare swung in an opposite direction the other member is effective by itsmagnetism to swing said armature in the other direction.

3. In combination with a vessel to contain liquid, a pair of spacedmagnetic members within the limiting confines of said vessel pivoted forunitary oscillation of said members in the plane thereof, means operablein response to rise of liquid in said vessel to move said members in onedirection, said means being arranged to move said members in theopposite direction upon fall of liquid level, and a switch armatureoutside the limiting confines of said vessel pivoted for oscillation inthe same general direction as said members and having cooperating meanslimiting cscillatory movements thereof and further having a portionthereof disposed with respect to said members so that when the latterare swung in one direction one of the members is efiectlve by itsmagnetism to swing the armature in one direction and when said membersare swung in the other direction the other member is efiective by itsmagnetism to swing said armature in the other direction.

4. A control switch mechanism comprising a permanent magnet ofsubstantially U-shape having a pair of spaced arms, said magnet beingpivoted for unitary oscillation of said arms in the plane thereof, aswitch armature pivoted intermediate its ends for oscillation in theplane of said magnet arms and having one end thereof extending betweensaid magnet arms, means limiting oscillatory movements of said armatureso that when the magnet arms are swung in one direction one of the armsis effective by its magnetism to swing said armature in one directionand when said magnet arms are swung in the opposite direction the otherarm is efiective by its magnetism to swing the armature in the oppositedirection, a contact carried by said armature, and a casing enclosingsaid armature and having a contact with which said armature contactcooperates.

5. A control switch mechanism for hydraulic accumulators for controllingthe water levels inside the pressure-chamber, comprising a diving belland a permanent magnet substantially of the horse-shoe type connectedwith said diving bell so as to constitute therewith an oscillatingassembly adapted to respond to the rise and fall of the water in saidpressure chamber, and a mercury tube switch extending from the outsideinto the wall of said pressure chamber and enclosing an oscillatingcontact armature, the inserted end of the tube of said switch projectingbetween the pole-pieces of said magnet and said armature being mountedwithin said tube for oscillation in the same general direction as themagnet so that said contact armature will swing in the plane of thepole-pieces of said magnet.

WILHELM PIRWITZ.

